CLARIUS HD3 - Page 55

Clarius Scanner HD3 Safety Topics
revision 9 48
after wearing latex gloves or inflating a toy balloon may be useful. For patients with
positive histories, flag their charts.
• If latex sensitivity is suspected, consider wearing a non-latex glove over the latex glove if
the patient is sensitive. If both the health professional and the patient are sensitive, a latex
middle glove could be used. (Latex gloves labeled “Hypoallergenic” may not always
prevent adverse reactions.)
• Whenever latex comes in contact with mucous membranes, be alert to the possibility of an
allergic reaction.
• If an allergic reaction does occur and latex is suspected, advise the patient of a possible
latex sensitivity, and consider an immunologic evaluation.
• Advise the patient to tell health professionals and emergency personnel about any known
latex sensitivity before undergoing medical procedures. Consider advising patients with
severe latex sensitivity to wear a medical identification bracelet.
Bioeffects
Thermal
Thermal bioeffects refers to heat generated whenever ultrasound energy is absorbed. The
amount of heat produced depends on the ultrasound's intensity, exposure time, and the
tissue's absorption characteristics.
Tissue absorbs ultrasound energy to varying degrees depending on the tissue's absorption
characteristics. Absorption characteristics are quantified by the absorption coefficient:
• Fluids: Their absorption coefficient is almost zero. Fluids such as amniotic fluid, blood, and
urine absorb very little ultrasonic energy. That means the ultrasound goes through the
fluid with very little decrease. And there's little temperature elevation in the fluid.
• Bone: Its absorption coefficient is very high. Dense bone absorbs the energy very quickly
and causes the temperature to rise rapidly. Adult bone absorbs nearly all acoustic energy
impinging on it. Fetal bone absorption coefficients vary greatly depending on the degree
of ossification.
• Soft tissue: Soft tissue varies in density depending on the organ, but the density does not
vary much within an organ. We call it soft tissue to distinguish it from hard tissue such as
bone. Also, the tissue density within a particular organ is not always the same. But for our
purposes, we assume that attenuation is uniform throughout the organ. We call this a
homogeneous soft tissue model.
Attenuation is caused by:
• Absorption: Energy converted to heat.
• Scattering: Redirection of ultrasound.